scholarly journals Influence of the Initial Grain Size on the Rolling and Recrystallization Textures in the Alloy Al-1.8% Cu

1995 ◽  
Vol 23 (2) ◽  
pp. 61-86 ◽  
Author(s):  
O. Engler
Keyword(s):  
Grain Size ◽  
Shear Bands ◽  
Spatial Density ◽  
Shear Band Formation ◽  
Band Formation ◽  
X Ray ◽  
Local Texture ◽  
Nucleation Sites ◽  
Large Particles ◽  
Deformation Models

The influence of the initial grain size prior to deformation on the rolling and recrystallization textures is investigated in the alloy Al-l.8wt%Cu by X-ray macrotexture analysis. Two different particle stages are examined: (i) Small shearable precipitates give rise to shear band formation and, during annealing, to nucleation of recrystallization at shear bands. (ii) Large particles cause particle stimulated nucleation of recrystallization (PSN). The microstructural evolution, particularly during recrystallization nucleation, is elucidated by metallographical investigations supported by EBSD local texture analysis.Both the initial grain size and the precipitation state strongly influence the evolution of the rolling textures. The results are interpreted with the help of Taylor-type deformation models. The recrystallization textures of Al-alloys emerge from a superposition of the orientations stemming from the various nucleation sites, i.e. Cube-bands, shear bands and particles. An increase of the initial grain size prior to deformation substantially shifts the recrystallization texture from the Cube-orientation towards the orientations being attributed to the other nucleation sites (shear bands, particles) which is interpreted by the spatial density of the various nucleation sites.

Rate dependence of serrated flow in a metallic glass

2003 ◽  
Vol 18 (4) ◽  
pp. 755-757 ◽  
Author(s):  
W. H. Jiang ◽  
M. Atzmon
Keyword(s):  
Plastic Deformation ◽  
Atomic Force Microscopy ◽  
Loading Rate ◽  
Shear Bands ◽  
Shear Band Formation ◽  
Band Formation ◽  
Serrated Flow ◽  
Force Microscopy ◽  
Loading Rates ◽  
Atomic Force

Plastic deformation of amorphous Al90Fe5Gd5 was investigated using nanoindentation and atomic force microscopy. While serrated flow was detected only at high loading rates, shear bands were observed for all loading rates, ranging from 1 to 100 nm/s. However, the details of shear-band formation depend on the loading rate.

The Effect of Cold Rolling Reduction on Shear Band and Texture Formation in Fe-3%Si Alloy

2012 ◽  
Vol 715-716 ◽  
pp. 158-163 ◽  
Author(s):  
Kenichi Murakami ◽  
N. Morishige ◽  
Kohsaku Ushioda
Keyword(s):  
Shear Band ◽  
Cold Rolling ◽  
Crystal Orientation ◽  
Shear Bands ◽  
Rolling Direction ◽  
Orientation Distribution ◽  
Rolling Reduction ◽  
Shear Band Formation ◽  
Band Formation ◽  
Cold Rolling Reduction

The effect of cold rolling reduction on shear band formation and crystal orientation within shear bands and annealing texture were investigated in Fe-3%Si {111}<112> single crystals. Several types of shear bands were observed with different angles to rolling direction, dependent on rolling reduction. As for shear band formation, those with smaller angles were formed earlier and those with larger angles were formed later. Regarding crystal orientation along shear bands after rolling reduction, orientation distribution from the initial became large in accordance with reduction and even exceeded Goss orientation when rolling reduction became larger than 40%. After annealing, however, recrystallized grains along shear bands were mainly Goss grains regardless of reduction. The speculated reason for the dominance of Goss after annealing is that Goss subgrains with less density of dislocations were surrounded by largely deformed areas.

scholarly journals Analyzing shear band formation with high resolution X-ray diffraction

2018 ◽  
Vol 147 ◽  
pp. 133-148 ◽  
Author(s):  
Darren C. Pagan ◽  
Mark Obstalecki ◽  
Jun-Sang Park ◽  
Matthew P. Miller
Keyword(s):  
High Resolution ◽  
Shear Band ◽  
Shear Band Formation ◽  
X Ray Diffraction ◽  
Band Formation ◽  
X Ray

Recrystallization Kinetics and Texture Evolution during Annealing of Cold Rolled Fe-Mn-C Alloy

2012 ◽  
Vol 715-716 ◽  
pp. 568-573 ◽  
Author(s):  
Ya Ping Lü ◽  
Dmitri A. Molodov ◽  
Günter Gottstein
Keyword(s):  
Texture Evolution ◽  
Shear Bands ◽  
X Ray Diffraction ◽  
X Ray ◽  
Recrystallization Kinetics ◽  
Nucleation Sites ◽  
Preferential Nucleation ◽  
Cold Rolled ◽  
Mechanical Twins

The recrystallization behavior of 50% cold rolled Fe-22%Mn-0.376%C alloy during annealing at 560°C, 630°C and 700°C was investigated. Microhardness tests were applied for characterization of the recrystallization kinetics, X-ray diffraction and EBSD measurements were utilized to characterize the crystallographic texture and the grain microstructure. The obtained experimental data were evaluated in terms of the JMAK model. The obtained values of the Avrami exponent varied in the range between 0.70 and 1.37. The inhomogeneous grain microstructure after recrystallization is interpreted in terms of non-randomly distributed nuclei. Shear bands, lamellar lines intersecting with mechanical twins and grain boundaries with localized high misorientation gradients were identified to be preferential nucleation sites. No pronounced texture was observed after annealing at 630°C.

scholarly journals Heat-Treatable Aluminum Alloys: Three-Point Bending

2019 ◽  
Author(s):  
Ida Westermann ◽  
Gaute Gruben
Keyword(s):  
Grain Size ◽  
Chemical Composition ◽  
Aluminum Alloys ◽  
Shear Band ◽  
Crack Propagation ◽  
Surface Topography ◽  
Shear Band Formation ◽  
Band Formation ◽  
Three Point Bending ◽  
Size And Morphology

In many applications within the automotive industry, the formability of sheets or extruded material is of great importance. The formability is strongly influenced by the chemical composition and the thermomechanical treatment prior to deformation. Grain size and morphology as well as texture and the presence of constituent particles make the material heavily anisotropic and the properties direction dependent. In all cases, shear band formation leads to surface topography during bending, and fracture initiates from the grooves. The crack propagation after initiation is, however, dependent on the grain size and the number and distribution of particles.

Analytical Modeling of Shear Localization in Orthogonal Cutting Processes

2021 ◽  
pp. 1-45
Author(s):  
Mohammadreza Fazlali ◽  
Mauricio Ponga ◽  
Xiaoliang Jin
Keyword(s):  
Shear Band ◽  
Orthogonal Cutting ◽  
Shear Bands ◽  
Chip Morphology ◽  
High Strength ◽  
Shear Localization ◽  
Shear Band Formation ◽  
Workpiece Material ◽  
Band Formation ◽  
Cutting Processes

Abstract This paper presents an analytical thermo-mechanical model of shear localization and shear band formation in orthogonal cutting of high-strength metallic alloys. The deformation process of the workpiece material includes three stages: homogeneous deformation, shear localization, and chip segmentation. A boundary layer analysis is used to analytically predict the temperature, stress, and strain rate variations in the primary shear zone associated with the shear localization. The predictions of shear band spacing and width from the proposed model are verified by experimental characterization of the chip morphology. The rolling of shear bands on the tool rake face is discussed from the experimental observations. The cutting tool temperature, which is influenced by the heat generated during the shear band formation, is simulated and compared with the finite element simulations. The proposed analytical model reveals the fundamental mechanism of the complete shear localization process in orthogonal cutting, and predicts the stress and temperature variations with high computational efficiency.

Large-Scale Deformation Patterning in Geomaterials Associated with Grain Rotation

2014 ◽  
Vol 891-892 ◽  
pp. 872-877 ◽  
Author(s):  
Maxim Esin ◽  
Arcady V. Dyskin ◽  
Elena Pasternak
Keyword(s):  
Shear Band ◽  
Degrees Of Freedom ◽  
Large Scale ◽  
Shear Bands ◽  
Physical Models ◽  
Image Correlation ◽  
Deformation Pattern ◽  
Shear Band Formation ◽  
Band Formation ◽  
Subsequent Formation

Modelling of large-scale deformation patterning in geomaterials is important for predicting instabilities and failures in the Earths crust. Shear band formation and the evolution of the bands is a predominant mechanism of deformation patterning. Independent rotations of separate grains/particles can affect the pattern formation by adding the effect of rotational degrees of freedom to the mechanism of instability. To model this mechanism we use a special experimental technique based on digital image correlation in order to recover both displacement and independent rotation fields in 2D physical models of granular material. In the physical model the particles are represented by smooth steel monodispersed disks with speckles painted on them to enable the rotation reconstruction. During the loading the deformation pattern undergoes stages of shear band formation followed by its dissolution due to re-compaction and particle rearrangement with the subsequent formation of multiple shear bands merging into a single one and the final dissolution. Also, patterns of rotations are observed at an intermediate scale between the scale of the particles and the scale of the shear band.

scholarly journals Molecular Dynamics Simulation of Structural Signals of Shear-Band Formation in Zr46Cu46Al8 Metallic Glasses

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2564
Author(s):  
Shi-Dong Feng ◽  
Keith Chan ◽  
Lei Zhao ◽  
Li-Min Wang ◽  
Ri-Ping Liu
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Shear Band ◽  
Metallic Glasses ◽  
Orientational Order ◽  
Shear Bands ◽  
Dynamics Simulation ◽  
Shear Band Formation ◽  
Band Formation ◽  
Average Size

The evolution from initiation to formation of a shear band in Zr46Cu46Al8 metallic glasses is presented via molecular dynamics simulation. The increase in number and the decrease in average size of clusters with the quasi-nearest atoms being 0 correspond to the shear-band evolution from initiation to formation. When the shear band is completely formed, the distribution of the bond orientational order q6 reaches a minimum. The maximum of the number of the polyhedral loss of Cu-centered <0, 0, 12, 0> and the minimum of the number of the polyhedral loss of Zr-centered <0, 2, 8, 5> correspond to the shear-band formation. These findings provide a strong foundation for characterizing the evolution from initiation to formation of shear bands.

scholarly journals ADAPTIVE FINITE ELEMENT COMPUTATIONS OF SHEAR BAND FORMATION

2010 ◽  
Vol 20 (03) ◽  
pp. 423-448 ◽  
Author(s):  
TH. BAXEVANIS ◽  
TH. KATSAOUNIS ◽  
A. E. TZAVARAS
Keyword(s):  
Finite Element ◽  
Shear Band ◽  
Shear Bands ◽  
Adaptive Finite Element ◽  
Shear Band Formation ◽  
Adaptive Finite Element Methods ◽  
Band Formation ◽  
Scaling Properties ◽  
Stress Diffusion ◽  
Variable Step

We study numerically an instability mechanism for the formation of shear bands at high strain-rate deformations of metals. We use a reformulation of the problem that exploits scaling properties of the model, in conjunction with adaptive finite element methods of any order in the spatial discretization and implicit Runge–Kutta methods with variable step in time. The numerical schemes are of implicit–explicit type and provide adequate resolution of shear bands up to full development. We find that from the initial stages, shear band formation is already associated with collapse of stress diffusion across the band and that process intensifies as the band fully forms. For fully developed bands, heat conduction plays an important role in the subsequent evolution by causing a delay or even stopping the development of the band.

Aspects of microanalysis in a transmission electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 510-511
Author(s):  
R. Sinclair ◽  
B.E. Jacobson
Keyword(s):  
Grain Size ◽  
Electron Beam ◽  
Electron Microscope ◽  
Chemical Analysis ◽  
Transmission Electron Microscope ◽  
Vapor Deposition ◽  
Critical Currents ◽  
X Ray ◽  
Fine Grain ◽  
Transmission Electron

INTRODUCTIONThe prospect of performing chemical analysis of thin specimens at any desired level of resolution is particularly appealing to the materials scientist. Commercial TEM-based systems are now available which virtually provide this capability. The purpose of this contribution is to illustrate its application to problems which would have been intractable until recently, pointing out some current limitations.X-RAY ANALYSISIn an attempt to fabricate superconducting materials with high critical currents and temperature, thin Nb3Sn films have been prepared by electron beam vapor deposition [1]. Fine-grain size material is desirable which may be achieved by codeposition with small amounts of Al2O3 . Figure 1 shows the STEM microstructure, with large (∽ 200 Å dia) voids present at the grain boundaries. Higher quality TEM micrographs (e.g. fig. 2) reveal the presence of small voids within the grains which are absent in pure Nb3Sn prepared under identical conditions. The X-ray spectrum from large (∽ lμ dia) or small (∽100 Ǻ dia) areas within the grains indicates only small amounts of A1 (fig.3).

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